This invention relates to an X-ray fluorescence coating thickness gauge which measures the thickness of metal coatings applied to electronic components etc. utilizing X-ray fluorescence.
Coating thickness gauges using X-ray fluorescence in the prior art measure coating thickness by observing the intensity of X-ray fluorescence generated from a test sample in response to irradiation of the coated surface of the sample, which has a coating film with one or a plural of components, with primary X-rays. An example of this procedure is shown in FIG. 2.
At first, a calibration curve is created. For this purpose, a standard sample is prepared as follows. On a base material which is the same as that of a sample to be subsequently measured, coatings of the same material as the sample to be subsequently measured are formed in two or three layers, or levels of thickness. The resulting standard sample is irradiated with primary X-rays and X-ray fluorescence which is generated by the irradiation is measured using an X-ray fluorescence coating thickness gauge. Then, the relations of measured intensity of X-ray fluorescence and coating thickness, which are the calibration curves, are acquired.
In the case where miscellaneous samples are intended to be measured by an X-ray fluorescence coating thickness gauge, the same standard samples with the same materials and the same coating materials as those for which measurement is expected should be made as above, and a plural number of calibration curves are stored in the memory means beforehand. Finally, the calibration curves thereof should be stored in the memory means in the X-ray fluorescence coating thickness gauge (filing of calibration curve data).
Next, test samples are measured. That is, the base materials and coating materials of samples for which coating thickness is to be measured by the gauge is verified (verification of sample ORIG). A calibration curve is selected out of calibration curve data stored and filed in the memory means referring to the same ORIG of the sample.
After setting a sample on the X-ray fluorescence coating thickness gauge X-ray fluorescence is detected by irradiation with the primary X-rays (sample measurement).
The coating thickness of the sample above is acquired referring to the intensity of fluorescence X-ray and the calibration curve which is selected (the measurement result).
In case that coating thickness of a sample is measured by using an X-ray fluorescence coating thickness gauge as explained in above, constituents of the sample should be known beforehand. Selection of the suitable calibration curve applicable for the purpose, out of curves which are organized beforehand, is required.
In case that coating thickness of a sample is to be measured by using an X-ray fluorescence coating thickness gauge, observers have to identify constituents of the sample (those of base materials and/or coating materials) and then to select and to determine a calibration curve out of those filed in the memory means thereof and to measure samples. Every time the constituents of samples to be measured changes, the calibration curve has to be selected again.